Leeches

Freshwater Fish, Pacific Northwest

Leeches, Photo By Bud Logan

Most people have a natural dislike for creatures making a habit of dining on living hosts. Like mosquitoes, black flies and deer flies are some noted favorites. Leeches also have this affect on most of us.

History portrays them as blood sucking creatures with a lousy reputation. But if you trace their roots back to medieval times where leeches were used for medicinal purposes, a practice that is still in use today, you will see that they have not always been thought of as demon creatures.

There are over 650 species worldwide. More than 60 species live in North America. They are cousins to terrestrial earthworms and night crawlers. Hardy and long lived for the most part leeches inhabit all of the BC Coastal Regions freshwater environments including, lakes, ponds, rivers, streams, bogs and swamps.

Muddy bottomed nutrient rich waters are home to prolific leech populations. Confident swimmers, they propel themselves through the water in an extended long, slender pitching motion and will walk like an inch worm across the bottom of lakes, possessing both anterior and posterior suckers leeches often use these to leapfrog along the bottom substrate and debris, the front sucker is actually their mouth.

Freshwater Leeches, Photo By Bud Logan

They also have the ability to dramatically vary their shape. Once threatened, they contract their 34 body segments, curling up in compact ball.

Most are carnivores, dining upon carrion, snails, insect larvae and nymphs. Some species have even evolved to feed on other leeches.

Camouflage masters, they feature mottled variegated color schemes to match their surroundings and avoid predators or to sneak up on unsuspecting prey.

Although possessing eyes, they have poor vision capable of only detecting variances in surrounding light levels. This shortfall is compensated through an acute sense of smell and touch.

Possessing both male and female sexual organs, they are hermaphroditic but must still mate in pairs, self fertilization is not possible. When mating, they can be seen intertwined and writhing around each other.